This season, The Mentalist has done two things simultaneously. It’s increased the degree of personal relationships among the regular characters, and it’s sharpened and refocused Simon Baker’s Patrick Jane — made him more intent than ever on solving crimes and, ultimately, getting his ultimate goal: the capture (and death?) of serial-killer Red John.

Last night — and if the headline above didn’t tip you off enough, here ya go: SPOILER ALERT, DON’T READ IF YOU DIDN’T WATCH LAST NIGHT! — we saw the deaths of a few characters, one of whom had been crucial to the season thus far.I had really enjoyed Terry Kinney’s guest run as Bosco, the slobbo cop with a bristly goatee and an even more bristly temper. The role could have been an ordinary grumpy-but-good police role, but Kinney took it up a notch with the way his wounded eyes belied his toughness, and the way his querulous line-readings made his sarcasm and combativeness less rude than intriguing.

So, too bad that he and his teammate Hicks were killed last night, done in by Rebecca (Shauna Bloom, in a bravely ego-free performance), who also worked for Bosco. Then, just as Jane and his crew had her under custody, she, too, died. Was she done in by Red John himself, in yet another devillish disguise? So we were left to believe, from the blissful smile on her face when she looked at the man who poisoned her.

Rebecca was “his red right hand” — that is, the person who did Red John’s bidding unquestioningly. There was a certain tidiness to the murders tonight: Swept away in one hour were all the new characters who’d dominated this story arc of The Mentalist, “so you could have the [Red John] case back,” as Rebecca told Jane.

But the convenience of the storytelling did not, ultimately, mar The Mentalist. The reverberations of last night’s hour will be felt for a while. Bosco’s confession to Lisbon that he loved her — and hers that she felt the same way — will have to play out in Robin Tunney’s performance in the weeks to come.

And Patrick Jane? Do you think he’ll feel guilt that he inspired these deaths, since Red John wanted Bosco and the others gone to give “the case back” to our hero?

People who don’t like The Mentalist complain that it’s too lightweight. But I think last night the producers made a strong move toward emphasizing the tragic undercurrent that runs beneath everything Patrick Jane does, and re-centers the series as a revenge drama with a lot of forward momentum. (We also saw the departure of Gregory Itzin’s Minelli — presumably so Itzen could have more time to appear in his beloved weasel-President role in 24‘s next season.)

How about you? Do you think last night’s actions will make the show even better, or will you miss Bosco?